The present invention relates to a guide wire assembly for intravascular investigations.
It is known to mount a sensor on a guide wire and to position the sensor via the guide wire in a body vessel in a living body to detect a physical parameter such as pressure or temperature. The sensor includes elements that are directly or indirectly sensitive to the parameter. For example, temperature could be measured by observing the resistance of a conductor having temperature sensitive resistance, or by observing the length of an element having a known temperature related elongation.
In order to monitor the state of the sensor inside the body some type of communication means is necessary. In some cases, means is also needed for providing power to the sensor and/or the communicating means.
Therefore, in order to power and communicate with the sensor a plurality of cables for transmitting measuring signals are connected to the sensor, and are routed along the guide wire to be passed out from the vessel to an external monitoring unit via a connector assembly. In addition, the guide wire is typically provided with a central metal wire (core wire) serving both as a support for the sensor and as a conductor of a ground potential.
However, the use of numerous cables requires that the core wire at least partly has to be replaced by a tubular section accommodating the cables. This section forms a weak part of the guide wire, and exhibits a risk for buckling during manipulation within the vessel as well as a risk for non-symmetrical behaviour.
Also, conventional guide wire assemblies exhibit a problem in that they require a very difficult manual assembling procedure. The extremely small components must be assembled under a microscope. This procedure is both tedious and labour intensive.
An improved guide wire, addressing some of these problems, is described in the European patent application EP 0 225 803. EP 0 925 803 describes a guide wire having generally tubular conductors being disposed concentrically around the core wire, thereby allowing a simplified manufacturing process. However, the manufacturing of such a guide wire is still comparatively time consuming and expensive. Such a guide wire further requires a complicated connector.
Therefore, there remains a need for a simplified guide wire assembly including a physical property sensor that is inexpensive, easily manufactured, and easy to manipulate.
It is the object of the present invention to provide a system for intravascular investigation of a physiological variable inside a living body including an easy-to-manufacture and easy-to-manipulate guide wire.
The invention reduces the number of electrical conduits necessary for a sensor guide wire, making the wire easy to manufacture and easy to use. The invention also contemplates a method for measuring physiological variables using the guide wire system.
A detailed description of the invention is given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only. From this detailed ii description various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.